Embodiments of the inventive subject matter generally relate to the field of communication systems and, more particularly, to signal power amplifiers used in communication systems.
A first communication device can transmit communication data to a second communication device through a communication medium. Examples of communication mediums can include power lines for Power Line Communications (PLC) and airwaves for wireless communications, such as wireless communications compliant with BLUETOOTH™, GSM, 3GPP or IEEE 802.11 specifications.
Transmitting data through the communication medium can consume substantial amounts power, particularly if communication data is transmitted as a wide bandwidth (e.g., 70 MHz or more) signal. Accurate linear data processing may increase the likelihood of successful transmission and reception of data. Commonly, class A or class A/B output stage topologies can be used to transmit the wide bandwidth communication data with good linearity, however class A or class A/B topologies can dissipate substantial amounts of power. A class A output stage can include circuits that are always biased on to conduct during all portions of an input cycle. Since the class A output stage is always conducting, even when input signals are quiescent, power is always being consumed. A class A/B output stage can include circuits arranged in a push-pull configuration that are biased on to conduct during positive and negative portions of the input cycle. Class A/B output stages can use slightly less power, compared to class A output stages, but can have increased distortion when the output crosses over from a positive portion to a negative portion. High levels of power dissipation can severely limit battery life and/or mobile operation of the communication device.